Sensitivity Analysis Strategy to Assess the Salting‐Out Problem during CO₂ Geological Storage Process

Abstract

The sensitivity analysis of the salting-out effect on well injectivity is a significant work in the research of geological storage of CO2 in deep saline aquifers, which is helpful in the selection of storage sites and the design of the injection strategy. We conduct a detailed sensitivity analysis about the salting-out process using the local sensitivity method and two global sensitivity methods. Sensitivity coefficients showed that brine salinity (XNaCl) has the highest sensitivity and interaction effect, the CO2 injection rate (QCO2) has a greater influence in the early stage of the salting-out process and a smaller influence in the end stage, and the other three parameters (empirical parameters related to the pore distribution m, the liquid residual saturation in the relative permeability function Splr, and the liquid residual saturation in the capillary pressure function Sclr) have a smaller sensitivity. This paper also analyzes the calculation amount of different sensitivity methods and suitable ways of obtaining the sensitivity coefficient and reveals the following. (1) The sensitivity coefficient changes dynamically with time, if only the sensitivity of the final state is taken into account on a long-time physical process, and some sensitive parameters during the process may be neglected. (2) The selection of the sample size should be based on the convergence of multiple calculations, and the results of the empirical calculation are uncertain. (3) The calculation of Sobol sensitivity is complicated, the results calculated by surrogate model depend on whether the sample is representative enough; on the other hand, it is feasible to use Sti-Si approximation to characterize the second-order sensitivity to reduce the computation. The research results not only reveal the sensitivity of the parameters related to the injection well salting-out problem during CO2 storage in deep saline aquifers but also guide the calculation of global sensitivity analysis with a similar physical process.

Assessment of Advanced Remediation Techniques for Enhanced CO2 Injectivity: Laboratory Investigations and Implications for Improved CO2 Flow in Saline Aquifers

“…The continuous evaporation of brine into the injected CO 2 stream during scCO 2 injection played a key role in the initial pressure drop observed during the core flooding experiments. This process, known as the salting-out effect, has been reported by several researchers. − This effect is driven by the decreased solubility of salts due to increased ionic strength in the CO 2 -brine mixture. In our study, continuous brine evaporation during scCO 2 injection led to the precipitation of salt crystals within the smaller pore spaces of the core.…”

Characteristics of Nitrogen Removal and Functional Gene Transcription of Heterotrophic Nitrification-Aerobic Denitrification Strain, Acinetobacter sp. JQ1004

“…At present, an increasing number of HNAD bacteria have been isolated and purified from different natural environments, such as Vibrio sp. [7], Zobellella sp. [8], and Pseudomonas sp.…”